Equity Incentive Plans - Stock-Based Compensation Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 32,219	$ 22,998
Cost of revenue—product
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	397	106
Cost of revenue—support
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	1,774	1,092
Research and development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	15,588	11,658
Sales and marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	10,626	7,519
General and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 3,834	$ 2,623